First, if you have not already done so, take your bird to an avian vet to make sure it is healthy. Your bird may be trying to tell you it doesn't feel well.
Usually birds are loud because they want your attention or at certain times of the day they just enjoy making noise. All birds should be allowed to make noise, it is in their DNA, but you CAN train them to not be noisy all day as long as they are healthy.
Please read the articles on our Parrot Training page for more information on training and parrot health.